Closing pool with high CYA

[daum]

It's definitely time to close my pool and is the first time I'll be doing so. I see we're suppose to SLAM it before, but I have a CYA of 140 in the pool which looks like it's saying put in 8 gallons of 12.5% bleach. Is there a way to do this so I'm not putting in so much (just is about 80 bucks worth of chlorine). Or is that really the only way forward?

Thanks!
Daum

 

[Texas Splash]

If you are confident the CYA is ~140 based on your TF-100 by performing a "diluted" CYA test, then increasing the FC is one way to go unless you wish to exchange some water first to lower the CYA which would probably be a waste. But you don't have to do an entire SLAM Process unless you currently have algae. If you do not have algae, simply increasing the FC once to an estimated FC of 56 just before shutting everything down should work. If you do not want to increase the FC that high, then you can increase the FC to about 24 and use a dosage of Polyquat 60 algaecide to help prevent algae growth.

Be sure to adjust the pH between 7.4-7.6 before increasing the FC.

 

[Mdragger88]

Slam level for your cya is 56ppm (40% of your cya) so if you’re currently at 12ppm fc then that is correct.
If you wish for the slam/shock level to be lower you will need to exchange some of your high cya water with fresh to reduce your cya level.
The point of raising to slam level is 2 fold- ensure anything active in the water is killed off & closing with enough fc to ensure that it doesn’t fall below minimum for your cya through the off season while closed.
Lots of folks use polyquat 60 to have a little insurance incase fc drops later. It’s added after fc has fallen about 1/2 way between target & slam level as mentioned in the closing article.

Closing an In Ground Pool

Winterizing a pool is essential for keeping your in-ground pool protected during cold-weather months. This Pool Repair guide will show you how to do it.

www.troublefreepool.com

If you are confident theres nothing hiding that might proliferate over the winter & are passing the Overnight Chlorine Loss Test
Then you could just go to 1/2way between target & slam with the fc & add polyquat 60.
The polyquat costs $ too so I am not sure there would be much savings there.

 

[Newdude]

+2. And keep in mind that FC of 10+ renders the PH test invalid. So let the FC drift under 10

 

[daum]

Ok thanks! We don't have any algae or issues currently. We're still in water restrictions here so can do a partial exchange, but will do another CYA test before we get to closing to see what it is, as we've had some rain lately. But will let the FC drive under 10 then do the PH test, then get enough chlorine to SLAM it properly.

Thanks, will also be back with questions on making sure I do the closing correctly too! Cyclone comes today! Probably will close next week.